Recently, a laser exposing apparatus so called an image setter is populated in the field of light-sensitive material for photomechanical output. When the exposure device of the exposing apparatus is a drum, it is usual that the silver halide photographic light-sensitive material, hereinafter simply referred to a light-sensitive material, is automatically rewound from the bulk roll and provided on the drum, and then fixed on the drum by vacuum suction and exposed to light.
In a practical case, the operating condition such as the period for exposure and the period from the completion of exposure to the start of next exposure are variously changed. The dimension of the light-sensitive material is frequently varied during the period in which the light-sensitive material is fixed by vacuum on the drum. Consequently, dimensions of the output images for yellow, magenta, cyan and black plates for color printing tend to differ from each other when one of the light-sensitive material is fixed for a prolonged time on the drum, even though the dimension of the four images have to the same.
Regarding the dimension stability of light-sensitive material, a technique for raising the dimension stability by improving the coating and drying conditions of the light-sensitive material has been disclosed in Japanese Patent Publication Open for Public Inspection, hereinafter referred to JP O.P.I., No. 1-130153. JP O.P.I. Nos. 1-315745, 2-108051 and 2-266355 disclose a technique for stabilizing the dimension from the viewpoint of the automatic processor.
However, these known techniques are the dimension stabilizing method for responding to change of dimension caused by the variation of the temperature and humidity of the environment and the condition of the automatic processor. The dimension stability relating the variation of the period of vacuum suction is not considered in these techniques, which is the object of the invention. Accordingly, further improvement has been demanded.